July 27 (Reuters) - Chilean commercial mall operator Mallplaza opened at 1,431 pesos on the local stock market, roughly flat from its initial public offering price (IPO) after raising $533 million in the biggest ever launch on the Chilean bourse.

The IPO put up 240 million shares - 12.5 percent of the company - which a Reuters poll of analysts said should sell for between 1,400 and 1,500 pesos.

Mallplaza, operates 21 malls in Chile, Peru and Colombia and is controlled by the Chilean retailer Falabella . (Reporting by Felipe Iturrieta and Antonio de la Jara Writing by Aislinn Laing Editing by Bill Trott)